1. Field of the Invention
This invention relates to a sun-interference suppression apparatus for optical imaging systems.
2. Description of the Prior Art
Optical and infrared detectors that operate by viewing or sensing a particular segment of the electromagnetic spectrum, must at times operate in the presence of extensive backgrounds of illuminated or radiated intensity, such as sunlight. The extensive background of the sun may be such that a detector may not distinguish the desired electromagnetic spectrum from the sunlit background.
Electronic means may be employed to reduce the background interference of the sun. A system that uses such electronic means is described in U.S. Pat. No. 3,204,100 entitled "Infrared Radiometer with Background Illumination", by Eric M. Wormser, et al., issued Aug. 31, 1965.
A system that uses optical means, such as an upper and lower field-of-view, in conjunction with electronic means to discern the effect of the sunlit background when viewing the horizon of the earth is described in U.S. Pat. No. 3,418,478 entitled "Horizon Sensor Using Two Stationary Fields of View Separated by a Fixed Elevation Angle which are Alternately Sampled," by Gerald Falbel, issued Dec. 24, 1968.
Neither of the aforementioned systems are able to suppress interference of the sunlit background with only optical means.